Myofascial pain and dysfunction is the most common diagnosis causing chronic head and neck pain. Both diagnosis and assessment of severity of this disorder rely on tenderness of muscle trigger points to manual palpation, a technique that has shown to be unreliable. A pressure algometer for muscle palpation (PAMP) was developed to allow more objective measurement of muscle tenderness and initial testing of it has shown it to be useful in quantifying tenderness. The aims of this proposal are to test the palpation technique using PAMP for interrater reliability and to evaluate its validity. Forty-five patients with myofascial pain and dysfunction will be tested for mean pain threshold of trigger points to palpation using PAMP by pairs of raters. Agreement between raters will be calculated to evaluate interrater reliability. Forty-five normal subjects, matched by age and sex, will also be tested and the results will be compared with results of MPD patients to determine differences. Construct validity will be supported if differences are found. If adequate reliability and validity are supported, the palpation technique with PAMP will be incorporated into the Craniomandibular Index, an objective measure of severity of craniomandibular pain and dysfunction.